Speedbit is also probably your default search engine too (you can Google how to change that) so first of all completely uninstall all Speedbit products from your computer. When reinstalling the programs deselect the option which should appear to make and keep Speedbit as your homepage and default browser. Its possible you didn't see it during installation, I didn't first time. They're nasty little pricks.

I have posted the solution here. Goto the last of the page and you shall find the solution.

https://support.mozilla.com/en-US/questions/797953#answer-169330